In this study cross-linked biocomposite with a high adsorption capacity was prepared by incorporating amorphous carbon thin film (ACTF); synthesized from rice straw by catalytic acid spray method; into the chitosan biopolymeric matrix by microwave irradiation precipitation technique. The new technique improves the polymeric cross-linking effect between ACTF and chitosan without catalyst and does not affect the spatial structure of chitosan. The physicochemical properties of the resulting biocomposite were evaluated by FTIR, SEM, XRD, Raman. The chitosan/ACTF biocomposite analyses refer to the presence of cave-shaped pores, high electron density and ion exchange active sites on internal and external surfaces in addition to high thermal stability. The adsorption study summarizes the potential of novel chitosan/ACTF biocomposite for the removal of Ca2+ and Ba2+ from water by batch adsorption. Freundlich isotherm model was best fitted to equilibrium data as well as the pseudo-second-order kinetic model was best fitted to adsorption kinetic data. Thermodynamic parameters (ΔG, ΔH, and ΔS) suggested the exothermic nature of Ca2+ and Ba2+ adsorption. The removal efficiency for Ca2+ and Ba2+ were 80% and 87.85 % at initial concentration of 100 mg/l, respectively. The results indicated that the chitosan/ACTF biocomposite has a high adsorption capacity and excellent water compatibility.